Fiber Optic Slickline and Tractor System

ABSTRACT

A system for delivering a fiber optic slickline through a deviated well with a battery powered tractor. The system includes a tractor having an efficiency rating of at least about 30% so as to adequately serve as a conveyance aid without the requirement of surface supplied power. For example, regulating of drive sections of the tractor may take place through a hydraulic section. Thus, arms of the tractor may be hydraulically locked in an open position without the requirement of continuous power to maintain the arms in an open position. At the same time, however, the hydraulic section may include accumulator capacity so as to allow for temporary responsive collapse of the arms for sake of navigating a restriction in the well.

BACKGROUND

Exploring, drilling and completing hydrocarbon and other wells aregenerally complicated, time consuming and ultimately very expensiveendeavors. In recognition of these expenses, added emphasis has beenplaced on efficiencies associated with well completions and maintenanceover the life of the well. Along these lines, added emphasis has beenplaced on well logging, profiling and monitoring of conditions from theoutset of well operations. Whether during interventional applications orat any point throughout the life of a well, detecting and monitoringwell conditions has become a more sophisticated and critical part ofwell operations.

Initial gathering of information relative to well and surroundingformation conditions may be obtained by way of a logging application.That is, equipment at the surface of an oilfield adjacent to the wellmay be used to deploy a logging tool in the well. Alternatively,straight forward temperature measurements may be taken by use of a fiberoptic line or tether. For example, as opposed to a generally morecomplex logging application, a distributed temperature survey (DTS) maybe undertaken with use of a fiber optic tether that may take locationspecific well temperature readings without the requirement of anassociated logging tool.

In the case of a vertical well, the fiber optic tether may be directlydropped into the well for sake of running a DTS application as notedabove. However, where the well is deviated, a conveyance aid such ascoiled tubing is generally utilized to help advance the tether throughtortuous regions of the well. For example, the tether may be jacketed bya metal tube and run through several thousand feet of coiled tubing.Thus, as the coiled tubing is forcibly injected through the tortuouswell, the fiber optic tether is also brought along for sake of the DTSapplication.

Unfortunately, coiled tubing is a dramatically cumbersome undertaking,particularly for the sake of no more than advancing a small lightweightfiber optic slickline through the well. Large scale equipment must bedelivered to the oilfield surface and properly rigged up in order toinject the coiled tubing. Once more, the coiled tubing introduces asubstantial restriction into the well. That is, the coiled tubing mayoccupy between about 1-3 inches in diameter of a well that is likelywell under 12 inches in diameter in certain locations. The degree ofobstruction here seems noteworthy when considering that for sake of theDTS application all that is required is conveyance of a fiber optictether that is generally under 0.125 inches in diameter.

With the above drawbacks in mind, fiber optics for a DTS application maybe incorporated into a more conventional wireline conveyance. Forexample, the wireline may be conveyed through tortuous well sections byway of conventional tractoring equipment. Specifically, a tractor may bepowered by an electrical cable run from the oilfield surface that alsoincorporates fiber optics for sake of the noted DTS application. Indeed,the wireline cable may include a variety of power and communicativelines along with a host of isolating and protective polymer layers. As aresult, the cable may be of relatively substantial weight, strength, andprofile.

Unfortunately, the use of such cables as described above again meansthat the equipment positioned at the surface of the oilfield may befairly substantial in terms of footprint and power requirementstherefor. Similarly, the set up and performance cost of running theoperation may also be quite significant. Further, while somewhat smallerthan coiled tubing, running such wireline still presents a substantialobstruction to the well. For example, it would not be unexpected for theline to be about 0.5 inches in diameter, well beyond what shouldactually be required for a slickline based fiber optic DTS application.

Presently, even though all that may be sought is a seemingly lightweightslickline DTS application, if the well is deviated, the operator'schoice is between one cumbersome equipment option or another. That is,either the large scale mobilization of coiled tubing equipment isrequired or the large scale mobilization of a heavy wireline cable andequipment is required. Either way, the well is more obstructed duringthe application and costs are substantially greater due to the addedequipment expenses.

SUMMARY

A tractor system is provided. The tractor system includes a downholepower source-operated tractor assembly that is configured for use in ahorizontal section of a well. A fiber optic slickline is coupled to thetractor assembly for obtaining measurements from the well. Additionally,the tractor assembly operates at an efficiency of greater than about30%, for example through use of discontinuous arm actuation techniques.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a side view of an embodiment of a fiber optic slickline andtractor system.

FIG. 1B is a side cross-sectional view of the system of FIG. 1Arevealing arm and conveyance actuation features for tractoring thereof.

FIG. 2A is an enlarged view of the arm and conveyance features of FIG.1B with tractor arms in a retracted position.

FIG. 2B is an enlarged view of the arm and conveyance features of FIG.2A with the tractor arms in an expanded position.

FIG. 3 is an overview of an oilfield with a deviated well accommodatingthe fiber optic slickline and system of FIG. 1.

FIG. 4 is a perspective view of the system of FIG. 3 in the well withexpanded tractor arms for centralizing and advancing of the systemthrough the well.

FIG. 5 is a flow-chart summarizing an embodiment of utilizing a fiberoptic slickline and tractor system.

DETAILED DESCRIPTION

Embodiments are described with reference to certain tools andapplications run in a well over a fiber optic slickline. As used herein,the term “slickline” is meant to refer to an application that is runover a conveyance line that is substantially below about 0.25 inches inoverall outer diameter and devoid of powered electrical communication.That is, as opposed to a higher profile or diameter wireline cable witha power line running therethrough, downhole applications detailed hereinare run over a lower profile slickline lacking such capacity. The typeof surface equipment dedicated to the slickline applications may be afairly mobile and of a comparatively smaller footprint as compared tothat required for wireline applications, discussed in more detail below.For example, the embodiments detailed herein utilize a fiber opticslickline for sake of distributed temperature survey (DTS) applications.However, such a fiber optic slickline may be coupled to a downholetractor and other tools that are of efficiencies tailored to run onconventional downhole batteries without reliance on surface deliveredpower for sake of operation. Further, measurements apart fromtemperature may be attained in manners detailed herein. For example,distributed pressure, strain, and/or vibration surveys applications mayalso be performed utilizing tools and techniques detailed herein.

Referring specifically now to FIG. 1A, a side view of an embodiment of afiber optic slickline and tractor system 100 is shown. The system 100includes a battery operated tractor 101, which may be, withoutlimitation, about 10-20 feet in length, which is connected to a fiberoptic slickline 110 as alluded to above. The slickline 110 is oflightweight construction and may be, without limitation, between about0.1 and 0.15 inches in diameter. The slickline 110 may include multiplefiber optic threads within a protective tubular structure. For example,one thread may be dedicated to telemetry such as for tractorcommunications, whereas another is dedicated to downhole measurements asdetailed herein, with still others provided for sake of redundancyand/or backup usage, etc. Regardless, as shown in FIG. 1, the tractor101 includes an interface 125 for accommodating a battery 120. Thus,while communications between the tractor 101 and equipment at anoilfield 300 may be served over the fiber optic slickline 110, powerrequirements for actually running the tractor 101 may be met by thebattery 120 (see FIG. 3). So, for example, where a DTS applicationutilizing the slickline 110 is run in a deviated well 380 as shown inFIG. 3 and detailed further below, the tractor 101 may serve as an aidto conveying the line 110 through the deviated well section. In anembodiment, the system 100 comprises a downhole embedded power sourceother than a battery 120 to power the tractor 101 such as, withoutlimitation, a hydraulic accumulator, a fuel cell, or the like.

In FIG. 1A an embodiment of the tractor 101 is shown as a wheeledtractor comprising elements or arms 135 configured to extend outwardlyfrom the tractor 101 and are shown in an expanded state in FIG. 1A. Withadded reference to FIG. 4, the arms 135 accommodate rollers or wheels137 that are configured for gripping a wall 400 of a well 380. Thus, asthe powered rollers 137 are turned, the tractor 101 may help the system100 advance (or retreat) in the well 380.

As depicted, the expanded arms 135 of the tractor 101 are visible at afirst drive section 130 thereof. However, the tractor 101 is alsooutfitted with another, second, drive section 140. Further, anypractical number of additional drive sections may also be incorporated.Regardless, the depicted second drive section 140 is also equipped witharms 135 and rollers 137 as is apparent in the perspective view of thetractor 101 in FIG. 4. However, for sake of providing centralization asdetailed further herein, the arms 135 of the different drive sections130, 140 may be perpendicular to one another. Thus, in the side view ofFIG. 1A, where the arms 135 of the first drive section 130 are entirelyvisible, those of the second drive section 140 are not apparent.

Continuing with reference to FIG. 1A, the tractor 101 is also outfittedwith a hydraulic section 175. That is, while the rollers 137 may bepowered by the battery 120 as needed, hydraulic control over armactuation may be utilized to substantially reduce the overall powerrequirements of the tractor 101 as detailed further below. As a result,the tractor 101 may be an effective and practical conveyance aid eventhough the power available to the tractor 101 is limited to what isavailable from conventional downhole batteries.

Referring now to FIG. 1B, a side cross-sectional view of the system 101of FIG. 1A is shown. In this view, roller 137 and arm 135 actuationfeatures are more apparent. For example, a motor 132 of the first drivesection 130 is shown. The motor 132 is solely powered by the battery120, which may be a conventional lithium ion type fit for downhole use.In one embodiment, the battery 120 is rechargeable. Further, even whenaccounting for another motor at the second drive section 140, the entiretractor 101 may operate at between about 150 and 300 watts which issufficiently met by the downhole battery 120. The tractor 101 may be ofan efficiency rating of at least about 30%. That is to say, less thanabout 70% of power consumed by the tractor 101 during operation may beattributed to heat and other non-performance losses. Additionally, inone embodiment, the battery 120 may be of a stackable configuration.That is, one or more additional battery modules may be provided inseries so as to increase power availability to the tractor 101.

The motors 132 are utilized to drive the rollers 137 as indicated above.Additionally, the hydraulic section 175 is motor powered. For example,as detailed below with reference to FIGS. 2A and 2B, a pump of thehydraulic section 175 may be motor powered to direct the arms 135 open.However, due to hydraulic regulation, the arms 135 may be hydraulicallylocked in an open position once expanded. Thus, a continuous power drainon the battery 120 need not take place in order to maintain the arms 135in an open position.

In the embodiment shown, the hydraulic section 175 includes acompensator or accumulator 160 to display hydraulic suspension behavior.So for example, where arms 135 in a locked open position encounter arestriction in the well 380, a small degree of temporary arm compressionmay take place so as to allow the tractor 101 to navigate therestriction. The end result is that, even though continuous motor driveis not used to maintain the arms 135 in an open position, the expandedarms 135 may display a similar type of responsiveness to potentiallychanging profile of the well 380 (see FIGS. 3 and 4).

Referring now to FIG. 2A, an enlarged view of the arm and conveyancefeatures of FIG. 1B are shown. Specifically, the internals of the firstdrive section 130 of the tractor 101 are shown as they would appear withthe tractor arms 135 in a retracted position. The hydraulic section 175of FIGS. 1A and 1B may be motor powered as described above (e.g. forregulating the expansion of the arms 135). Similarly, the depicted motor132 is also in direct mechanical communication with the rollers 137 ofFIGS. 1A and 1B for rotation thereof to drive the tractor 101. However,as described further below, the separate functions of roller rotationand arm actuation are intentionally disassociated for sake of maximizingtractor efficiency in terms of power requirements.

Continuing with reference to FIG. 2A, with added reference to FIG. 1B,the motor 132 is linked to the rollers 137 through a rotating shaft 210that interfaces gearing 250 ultimately reaching the rollers 137, thoughalternate mechanical linkage architecture may be used. Regardless,surface directed actuation of the rollers 137 may take place viacommunication over the slickline 110. Similarly, motor powered fluidcommunication with the hydraulic section 175 may translate intohydraulic control over the position of a linear piston 225 that servesto open or expand the arms 135 to the position shown in FIG. 2B.However, since this function is regulated through the hydraulic section175, a pump need not be continuously driven to keep the arms 135 open.

With specific reference to FIG. 2B, an enlarged view of tractorinternals are depicted with the arms 135 in an expanded or openposition. In the embodiment shown, this is achieved through hydraulicshifting of the linear piston 225 in an uphole direction. When thisoccurs, actuator rods 275 coupled to the piston 225 are pulled upward ina manner that shifts open the arms 135 about an axis at the above-notedgearing 250. Of course, alternative types of architecture and/ororientation may be utilized. However, by utilizing some form ofintervening hydraulics to actuate opening of the arms 135, theopportunity to hydraulically lock the arms in the open position is nowavailable. Thus, dramatic savings may be realized in terms of powerconsumption and battery life.

So, for example, at the appropriate time an operator at an oilfield 300may send data over the fiber optic slickline 110 to direct the batterypowered driving of a pump of the hydraulic section 175 to open the arms135 as described (see FIGS. 1B and 3). Once opened, the operator may nowdirect a hydraulic locking of the arms 135 in the open position suchthat no further motor drive or power is required in order keep the armsin this open position.

Continuing with added reference to FIG. 1B, with the arms 135 expandedthe operator may now signal the motor 132 to drive rotation of therollers 137 through the rotating shaft 210 and gearing 250. Thus, whenengaged with a well wall 400 as shown in FIG. 4, an aid to system 100advancement through the well 380 is now provided. Indeed, the motor 132may also be directed to rotate the rollers 137 in a reverse direction tohelp in removal of the system 100 from the well 380. Although, it may bemore common to direct opening of the hydraulic lock to allow collapse orretraction of the arms 135 followed by winch driven removal of theentire system 100 from the well 380 by pulling uphole on the slickline110 (see FIG. 3). While embodiments of the tractor 101 are shown aswheeled tractors comprising drive sections 130 and 140 utilizing arms135 and rollers 137, the fiber optic slickline 110 and system 100 mayutilize a tractor 101 having drive sections similar a reciprocating-typetractor, such as that shown in U.S. Pat. No. 6,629,568, incorporated byreference herein in its entirety, while remaining within the scope ofthe present disclosure. In such an embodiment the battery may beutilized to power hydraulic section, similar to the hydraulic section175, which may be locked utilizing an accumulator, such as theaccumulator 160 noted hereinabove. In an embodiment, manipulation of theslickline 110 may be utilized to advance and/or assist in advancing thesystem 100 through the wellbore.

Referring now to FIG. 3, an overview of an oilfield 300 is shown with adeviated well 380 that accommodates the fiber optic slickline 110 andsystem 100 of FIG. 1. In the embodiment shown, the tractor 101 of thesystem 100 is utilized to help convey the slickline 110 through thedeviated portion of the well 380 in order to carry out a DTSapplication. Thus, information regarding well characteristics may beacquired by fiber optics of the slickline 110 and and performancecharacteristics of the tractor 101 may be transmitted from the tractor101 and analyzed by a processor of a control unit 330 at the surface ofthe oilfield 300. The slickline 110 also may be configured Additionally,in other embodiments, a service tool 145 or other application device mayalso be secured to the tractor for carrying out additional applicationsin the well 380 as directed over the slickline 110 and/or powered by thedownhole battery 120 as shown in FIGS. 1A and 1B. The service tool 145may comprise, but is not limited to, a mechanical services toolconfigured for plug setting or for manipulating downhole completioncomponents, a logging tool, a perforating tool, or any suitable downholetool.

Fiber optic communications to a receiver of the tractor 101 from thecontrol unit 330 may be sent over the slickline 110 to direct andcontrol specific maneuvers during conveyance, such as in response toperformance characteristics transmitted to the control unit 330 from thetractor 101 along the slickline. Specifically, the drive sections 130,140 of the tractor 101 may be directed independently or in concert asdescribed hereinabove. For example, advancement of the system 100 maycease, the arms 135 opened, locked, and the rollers 137 rotated to beginaiding conveyance as the tractor 101 approaches the horizontal wellsection, all directed from the surface-based control unit 330.

In the embodiment shown, a truck 325 is utilized to accommodate thenoted control unit 330 along with a spool 340 of fiber optic slickline110. While other delivery modes may be utilized, the type of surfaceequipment dedicated to the application may be a fairly mobile and of acomparatively smaller footprint (with respect to typical wireline orcoiled tubing surface equipment) given the lightweight nature of theslickline 110. Further, the use of a suitable battery powered tractor101 that is compatible with the slickline 110 avoids detracting from thesmall profile and lightweight advantages of the slickline 110. Morespecifically, the slickline 110 is run past a conventional rig 350 andpressure control equipment 375. Casing 385 defining the deviated well380 traverses various formation layers 390, 395 perhaps extendingseveral thousand feet in depth. Yet, the highly efficient, power savingtractor 101 is capable of pulling the slickline 110 throughout the well380 for the DTS application, perhaps even serving as an aid towithdrawal of the system 100 when the application is completed. In anembodiment where two drive sections 130, 140 are utilized as depicted, apull force of 200-300 lbs. may be available with an expected speed ofmore than about 1,000 ft. per hour provided.

Referring now to FIG. 4, a perspective view of the system 100 of FIG. 3is shown in the well 380. In this view, the expanded tractor arms 135 ofboth drive sections 130, 140 are simultaneously visible. In addition tothe interfacing at the well wall 400 that is apparent between teeth ofthe rollers 137 and the casing 385 for sake of conveyance, theorientation of the drive sections 130, 140 relative one another is nowmore apparent. More specifically, the role of centralizing the tractor101 in the well 380 is more clear with each section 130, 140 of asubstantially perpendicular orientation (with respect to a longitudinalaxis of the tractor 101) to the next, thereby preventing the tractor 101from becoming misaligned from a central axis of the well 380.

The view of the tractor 101 in the well 380 as shown in FIG. 4 alsoreveals its generally small profile. That is, the tractor 101 mayoperate on no more than a downhole battery 120 as detailed above (seeFIGS. 1A and 1B). Thus, it may be fairly small, with a body of perhapsbetween about 2-3.5 inches in overall diameter (d). This is in contrastto an overall well diameter (D) that is likely to exceed 10 inches. So,for example, in contrast to a larger coiled tubing operation, the flowrate of the well 380 is unlikely to be substantially affected by thepresence of the tractor 101 or the slickline 110 (see FIG. 3).Similarly, the slickline 110 of FIG. 3 is not separated from the wellenvironment by coiled tubing. Thus, a more accurate DTS application maytake place, with readings likely within about 3° F. of actualtemperature, in addition to one that is less cumbersome and morecost-effective. In addition to or complementing the distributedtemperature, distributed pressure, distributed strain, and/ordistributed vibration measurements, in an embodiment, the tractor 101may convey the slickline 110 to a predetermined location within a well,such as the well 380 and remain in the predetermined location for apredetermined length of time in order to perform a production loggingoperation. Such a production logging operation may be performedutilizing distributed temperature, distributed pressure, distributedstrain, and/or distributed vibration measurements without substantiallyoccluding the well 380 during production therefrom.

Referring now to FIG. 5, a flow-chart summarizing an embodiment ofutilizing a fiber optic slickline and tractor system is depicted. In theembodiment shown, the system is deployed into a well as indicated at 515and utilized in an application to acquire well information (see 525).For example, a DTS application may be run with well temperatureprofiling taking place directly through a fiber optic slickline of thesystem. Indeed, such data acquisition may ensue as soon as the system isdeployed into the uppermost vertical section of the well.

Given that the system is also outfitted with a battery operated tractorassembly, applications such as the noted DTS may also be run in anydeviated section of the well. Specifically, without any direct powerfrom surface, arms of the tractor may be opened as indicated at 535 tobegin engagement with a wall of the well. As a matter of enhancing powerefficiency, the arms are opened and may even be locked in position in ahydraulic fashion (see 545). Thus, as indicated at 555, rollers on thearms may be directed to rotate and aid in advancement of the tractor andsystem through the deviated section of the well. In one embodiment, thehydraulics of the system incorporate an accumulator that allows for adegree of arm collapse upon encountering a predetermined amount ofresistive force. So, for example, as the tractor encounters arestriction, the arms may collapse radially inwardly to a predetermineddegree to allow for the continued advancement of the tractor as opposedto having the entire system stuck in place at the location of therestriction.

As indicated at 565, additional, perhaps more directly interventional,applications may also be performed with a service tool that isincorporated with the system. Regardless, once the downhole applicationsare completed, the system may be removed from the well. Morespecifically, the rollers may be directed to cease any advancingrotation, the hydraulic lock lifted, and the arms retracted into thebody of the tractor, with each of these maneuvers directed over thefiber optics of the slickline. Thus, as indicated at 575 the entiresystem may be pulled out of the well in a winch-driven fashion by aspool at the oilfield surface adjacent the well. Additionally, in anembodiment as indicated at 585, roller rotation may be reversed with thearms remaining in an open position to serve as a further aid towithdrawal of the system from the well. This type of aided withdrawalmay serve as a safeguard against damage to the lighter weight slickline.

Embodiments of the fiber optic slickline and tractor system detailedherein allow for avoiding the use of heavier cables and correspondinglylarger tractors where the operator is faced with running a DTS or otherlow power application in a deviated well. Similarly, the use of coiledtubing may also be avoided. Thus, the time, expense and footspacededicated to large scale interventional equipment may also be avoided.Indeed, even the amount of wellbore space that is occupied duringdownhole applications run over the fiber optic slickline and tractorsystem may be kept to a minimum. Thus, flow through the well during suchapplications may remain largely unobstructed. In an embodiment, thefiber optic slickline may be deployed within the flow path of a coiledtubing and the tractor system of the present disclosure may be attachedto the downhole end of the coiled tubing to aid in tractoring the coiledtubing through a wellbore, such as a deviated wellbore or the like.

The preceding description has been presented with reference to presentlypreferred embodiments. Persons skilled in the art and technology towhich these embodiments pertain will appreciate that alterations andchanges in the described structures and methods of operation may bepracticed without meaningfully departing from the principle, and scopeof these embodiments. Regardless, the foregoing description should notbe read as pertaining only to the precise structures described and shownin the accompanying drawings, but rather should be read as consistentwith and as support for the following claims, which are to have theirfullest and fairest scope.

We claim:
 1. A system comprising: a tractor for disposal in a deviatedwell; and a fiber optic slickline coupled to said tractor.
 2. The systemof claim 1 wherein said tractor comprises a downhole power source tooperate the tractor.
 3. The system of claim 1 wherein said fiber opticslickline is configured to obtaining measurements from the well.
 4. Thesystem of claim 1 wherein said fiber optic slickline is configured tocontrol movement of said tractor through the well.
 5. A fiber opticslickline tractor assembly for disposal in a well, the assemblycomprising: a main body; a battery housed by said main body; a drivesection incorporated into said main body to obtain power from saidbattery for moving the assembly within a deviated section of the well;and a hydraulic section coupled to said main body for directingengagement with a wall of the well for the moving of the assembly, thedirecting of the engagement in a manner conserving power available fromsaid battery.
 6. The assembly of claim 5 wherein wherein said battery isof a stackable configuration to allow coupling of an additional batterythereto.
 7. The assembly of claim 5 wherein the drive section comprisesone of a wheeled tractor and a reciprocating tractor.
 8. The assembly ofclaim 7 wherein said drive section comprises: an arm for extending to aposition away from said main body to attain the engaging with the wellwall; a roller coupled to said arm and for interfacing a wall of thewell during the extending of said arm; and a motor poweringly coupled tosaid roller through said arm to rotate said roller during theinterfacing with the wall to aid in the moving of the assembly.
 9. Theassembly of claim 5 wherein the fiber optic slickline is configured toconduct signals between a surface of the well and the tractor assemblyto direct the engagement of the tractor and thereby control movement ofsaid tractor through the well.
 10. The assembly of claim 8 wherein saidhydraulic section comprises a locking mechanism to secure said arm inthe extended position during the moving of the assembly.
 11. Theassembly of claim 10 wherein said hydraulic section comprises anaccumulator to allow a degree of collapse by said arm from the extendedposition upon encountering a predetermined level of resistance.
 12. Theassembly of claim 7 wherein said drive section is a first drive section,the assembly further comprising a second drive section incorporated intosaid main body to obtain power from said battery for moving the assemblywithin the deviated section.
 13. The assembly of claim 12 wherein saidarm is a first arm of said first drive section, the assembly furthercomprising a second arm of said second drive section for extending to aposition away from said main body in a manner substantiallyperpendicular to said first arm as an aid to centralization of theassembly within the well.
 14. A method of performing a distributedmeasurement survey application in a well, the method comprising:deploying a fiber optic slickline and tractor system into a well; andtaking measurement readings within the well via the fiber opticslickline.
 15. The method of claim 14 further comprising performinganother application in the well with a service tool coupled to thesystem.
 16. The method of claim 14 wherein the distributed measurementsurvey application is directed at one of temperature, pressure, strainand vibration measurements.
 17. The method of claim 14 furthercomprising using a downhole battery of the system to power said tractorsystem.
 18. The method of claim 14 wherein the tractor system comprisesone of a wheeled tractor and a reciprocating tractor.
 19. The method ofclaim 18 wherein deploying comprises deploying a tractor systemcomprising at least one drive section, the drive section comprising atleast one element configured to engage with the wall of the well andfurther comprising compensatingly collapsing the element to a degreeupon encountering a predetermined amount of resistive force presented bya restriction in the well.
 20. The method of claim 18 further comprisingremoving the system from the well by one of: powering the tractor in areverse direction; and pulling on the slickline from a location at anoilfield surface adjacent the well.